A droplet actuator is an example of digital microfluidics technology. A droplet actuator typically includes one or more substrates configured to form a surface or gap for conducting droplet operations. The one or more substrates establish a droplet operations surface or gap for conducting droplet operations and may also include electrodes arranged to conduct the droplet operations via electrowetting. The droplet operations substrate or the gap between the substrates may be coated or filled with a filler fluid that is immiscible with the liquid that forms the droplets. Digital microfluidics devices have been used to conduct a variety of molecular protocols such as amplification of nucleic acids (e.g., quantitative polymerase chain reaction (qPCR)) and nucleic acid sequencing. A digital microfluidic protocol for performing a biochemical reaction typically includes the electrowetting-induced transport and mixing of an aqueous sample and reagent droplets in an immiscible fluid, such as oil, in a droplet actuator.